The Thrombolysis in Myocardial Ischemia (TIMI III) studies consist of two multicenter, randomized controlled clinical trials in patients with unstable angina or non-Q-wave myocardial infarction. TIMI III A is a double-blind comparison of recombinant tissue plasminogen activator (t-PA) to placebo for improvement of coronary artery stenosis and perfusion. TIMI III B will compare, in a 2x2x2 factorial design, double-blind treatment with t-PA or placebo, known treatment with or without heparin, and management with or without cardia catheterization (and percutaneous transluminal coronary angioplasty or coronary artery bypass graft surgery, if appropriate) at 24-48 hours after presentation for the prevention of death, subsequent myocardial infarction, disabling stroke or treatment failure as defined by the results of ambulatory ECG monitoring, exercise testing and clinical observations. After three months of planning and study start up, TIMI III A Investigators will start recruitment to achieve a goal of 300 patients in nine months; and TIMI III B Investigators will start recruitment to achieve a goal of 2,000 patients in 24 months. Upon completion of TIMI III A recruitment, TIMI III A Clinical Centers may participate in the TIMI III B Protocol. The last year of this four-year project will be dedicated to data analysis and preparation of presentations and publications. This application is to support the Coordinating Center at the Maryland Medical Research Institute. The Coordinating Center will be responsible for treatment assignments, supervision of the Drug Distribution Center, monitoring Core Laboratories, direction of an Adverse Events Classification Committee, rapid communication and generation of performance data for review with the Principal Investigator's Office, and data analysis to assess treatment and management strategy effects. An independent Safety and Data Monitoring Committee, appointed by the National Heart, Lung and Blood Institute (NHLBI), will meet at regular intervals to review both performance data and treatment results to advise the TIMI III Investigators and NHLBI leadership on the conduct of the study.